Hi, guys, in fact this is the same noise I asked before, if you remember. But I think I can give it a better description today. It sounds like plastics rubbing slow running fan blades or maybe sometimes like aluminum rubbing fan blades. It's at the left (driver) front tire area. The frequency is roughly once or twice per second. It only happens on some of the days. When it happens, I can't hear it <15 mph. I can't hear it >45 mph either, probably because of wind noise (so it's not loud at all). It tends to happen more often on a cold day after right cold start. After a good run, it might go away. Braking (even a very gentle one) will stop the noise for sure. It probably only happens when going straight but I am not 100% positive. It's probably not because of the engine because even I run the engine at 2000 rpm at park, I can't hear anything. I have jacked up the car but couldn't find anything really suspicious. Oh, yes, this is a 2000 A6 2.7t w/ tip, 133 k miles, no chipped. So I wonder if you guys have any idea. Thank you very much!